/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

import type {LoadedVersion, LoadedContent} from './types';
import type {
  Sidebar,
  SidebarItemCategory,
  SidebarItemCategoryLink,
  Sidebars,
} from './sidebars/types';

import {chain, mapValues, keyBy} from 'lodash';
import {
  collectSidebarCategories,
  transformSidebarItems,
  collectSidebarLinks,
} from './sidebars/utils';
import type {
  TranslationFileContent,
  TranslationFile,
  TranslationFiles,
  TranslationMessage,
} from '@docusaurus/types';
import {mergeTranslations} from '@docusaurus/utils';
import {CURRENT_VERSION_NAME} from './constants';

function getVersionFileName(versionName: string): string {
  if (versionName === CURRENT_VERSION_NAME) {
    return versionName;
  }
  // I don't like this "version-" prefix,
  // but it's for consistency with site/versioned_docs
  return `version-${versionName}`;
}

// TODO legacy, the sidebar name is like "version-2.0.0-alpha.66/docs"
// input: "version-2.0.0-alpha.66/docs"
// output: "docs"
function getNormalizedSidebarName({
  versionName,
  sidebarName,
}: {
  versionName: string;
  sidebarName: string;
}): string {
  if (versionName === CURRENT_VERSION_NAME || !sidebarName.includes('/')) {
    return sidebarName;
  }
  const [, ...rest] = sidebarName.split('/');
  return rest.join('/');
}

/*
// Do we need to translate doc metadata?
// It seems translating front matter labels is good enough
function getDocTranslations(doc: DocMetadata): TranslationFileContent {
  return {
    [`${doc.unversionedId}.title`]: {
      message: doc.title,
      description: `The title for doc with id=${doc.unversionedId}`,
    },
    ...(doc.sidebar_label
      ? {
          [`${doc.unversionedId}.sidebar_label`]: {
            message: doc.sidebar_label,
            description:
              `The sidebar label for doc with id=${doc.unversionedId}`,
          },
        }
      : undefined),
  };
}
function translateDoc(
  doc: DocMetadata,
  docsTranslations: TranslationFileContent,
): DocMetadata {
  return {
    ...doc,
    title: docsTranslations[`${doc.unversionedId}.title`]?.message ?? doc.title,
    sidebar_label:
      docsTranslations[`${doc.unversionedId}.sidebar_label`]?.message ??
      doc.sidebar_label,
  };
}

function getDocsTranslations(version: LoadedVersion): TranslationFileContent {
  return mergeTranslations(version.docs.map(getDocTranslations));
}
function translateDocs(
  docs: DocMetadata[],
  docsTranslations: TranslationFileContent,
): DocMetadata[] {
  return docs.map((doc) => translateDoc(doc, docsTranslations));
}
 */

function getSidebarTranslationFileContent(
  sidebar: Sidebar,
  sidebarName: string,
): TranslationFileContent {
  type TranslationMessageEntry = [string, TranslationMessage];

  const categories = collectSidebarCategories(sidebar);

  const categoryContent: TranslationFileContent = Object.fromEntries(
    categories.flatMap((category) => {
      const entries: TranslationMessageEntry[] = [];

      entries.push([
        `sidebar.${sidebarName}.category.${category.label}`,
        {
          message: category.label,
          description: `The label for category ${category.label} in sidebar ${sidebarName}`,
        },
      ]);

      if (category.link) {
        if (category.link.type === 'generated-index') {
          if (category.link.title) {
            entries.push([
              `sidebar.${sidebarName}.category.${category.label}.link.generated-index.title`,
              {
                message: category.link.title,
                description: `The generated-index page title for category ${category.label} in sidebar ${sidebarName}`,
              },
            ]);
          }
          if (category.link.description) {
            entries.push([
              `sidebar.${sidebarName}.category.${category.label}.link.generated-index.description`,
              {
                message: category.link.description,
                description: `The generated-index page description for category ${category.label} in sidebar ${sidebarName}`,
              },
            ]);
          }
        }
      }

      return entries;
    }),
  );

  const links = collectSidebarLinks(sidebar);
  const linksContent: TranslationFileContent = chain(links)
    .keyBy((link) => `sidebar.${sidebarName}.link.${link.label}`)
    .mapValues((link) => ({
      message: link.label,
      description: `The label for link ${link.label} in sidebar ${sidebarName}, linking to ${link.href}`,
    }))
    .value();

  return mergeTranslations([categoryContent, linksContent]);
}

function translateSidebar({
  sidebar,
  sidebarName,
  sidebarsTranslations,
}: {
  sidebar: Sidebar;
  sidebarName: string;
  sidebarsTranslations: TranslationFileContent;
}): Sidebar {
  function transformSidebarCategoryLink(
    category: SidebarItemCategory,
  ): SidebarItemCategoryLink | undefined {
    if (!category.link) {
      return undefined;
    }
    if (category.link.type === 'generated-index') {
      const title =
        sidebarsTranslations[
          `sidebar.${sidebarName}.category.${category.label}.link.generated-index.title`
        ]?.message ?? category.link.title;
      const description =
        sidebarsTranslations[
          `sidebar.${sidebarName}.category.${category.label}.link.generated-index.description`
        ]?.message ?? category.link.description;
      return {
        ...category.link,
        title,
        description,
      };
    }
    return category.link;
  }

  return transformSidebarItems(sidebar, (item) => {
    if (item.type === 'category') {
      const link = transformSidebarCategoryLink(item);
      return {
        ...item,
        label:
          sidebarsTranslations[`sidebar.${sidebarName}.category.${item.label}`]
            ?.message ?? item.label,
        ...(link && {link}),
      };
    }
    if (item.type === 'link') {
      return {
        ...item,
        label:
          sidebarsTranslations[`sidebar.${sidebarName}.link.${item.label}`]
            ?.message ?? item.label,
      };
    }
    return item;
  });
}

function getSidebarsTranslations(
  version: LoadedVersion,
): TranslationFileContent {
  return mergeTranslations(
    Object.entries(version.sidebars).map(([sidebarName, sidebar]) => {
      const normalizedSidebarName = getNormalizedSidebarName({
        sidebarName,
        versionName: version.versionName,
      });
      return getSidebarTranslationFileContent(sidebar, normalizedSidebarName);
    }),
  );
}
function translateSidebars(
  version: LoadedVersion,
  sidebarsTranslations: TranslationFileContent,
): Sidebars {
  return mapValues(version.sidebars, (sidebar, sidebarName) =>
    translateSidebar({
      sidebar,
      sidebarName: getNormalizedSidebarName({
        sidebarName,
        versionName: version.versionName,
      }),
      sidebarsTranslations,
    }),
  );
}

function getVersionTranslationFiles(version: LoadedVersion): TranslationFiles {
  const versionTranslations: TranslationFileContent = {
    'version.label': {
      message: version.versionLabel,
      description: `The label for version ${version.versionName}`,
    },
  };

  const sidebarsTranslations: TranslationFileContent =
    getSidebarsTranslations(version);

  // const docsTranslations: TranslationFileContent =
  //   getDocsTranslations(version);

  return [
    {
      path: getVersionFileName(version.versionName),
      content: mergeTranslations([
        versionTranslations,
        sidebarsTranslations,
        // docsTranslations,
      ]),
    },
  ];
}
function translateVersion(
  version: LoadedVersion,
  translationFiles: Record<string, TranslationFile>,
): LoadedVersion {
  const versionTranslations =
    translationFiles[getVersionFileName(version.versionName)].content;
  return {
    ...version,
    versionLabel: versionTranslations['version.label']?.message,
    sidebars: translateSidebars(version, versionTranslations),
    // docs: translateDocs(version.docs, versionTranslations),
  };
}

function getVersionsTranslationFiles(
  versions: LoadedVersion[],
): TranslationFiles {
  return versions.flatMap(getVersionTranslationFiles);
}
function translateVersions(
  versions: LoadedVersion[],
  translationFiles: Record<string, TranslationFile>,
): LoadedVersion[] {
  return versions.map((version) => translateVersion(version, translationFiles));
}

export function getLoadedContentTranslationFiles(
  loadedContent: LoadedContent,
): TranslationFiles {
  return getVersionsTranslationFiles(loadedContent.loadedVersions);
}
export function translateLoadedContent(
  loadedContent: LoadedContent,
  translationFiles: TranslationFile[],
): LoadedContent {
  const translationFilesMap: Record<string, TranslationFile> = keyBy(
    translationFiles,
    (f) => f.path,
  );

  return {
    loadedVersions: translateVersions(
      loadedContent.loadedVersions,
      translationFilesMap,
    ),
  };
}